TV channels can be watched from DD terminals with the following ESCAPE commands.

    ESC n K   Watch and listen to TV channel n (n=2 to 83).
    ESC 0 K   Turn off TV at this DD (like ESC S, ESC U).
    BRK n K   Watch TV channel n without turning on its sound.
    BRK 0 K   Match TV audio and video, if only one is being received.
    ESC K     Tune in next higher available TV channel.
    BRK K     Tune in next lower available TV channel.

If you finish watching TV, please type ESC 0 K (or equivalent) to free
up that tuner, so that it can be changed to other channels.  Leaving an
unwatched DD mapped to a TV keeps that TV tuner locked to its current channel
and thus cuts into the flexibility of the system.